<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>三色色子</title>
</head>
<style>
  .box{
    height: 200px;
    width: 200px;
    border: 1px solid #000;
    border-radius: 8px;

    display: flex;
    justify-content: space-between;
  }

  .item{
    display: block;
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background-color: #666;
  }

  :nth-child(2){
    align-self: center;
  }
  :nth-child(3){
    align-self: flex-end;
  }
</style>
<body>

  <div class="box">
    <span class="item"></span>
    <span class="item"></span>
    <span class="item"></span>
  </div>

</body>

</html>